can I create a class dynamically with $? (dollar-sign) - php

Question

In PHP sometimes it would be nice if I could define a function or a class with a variable name like
$myfunctionname="test";
function $myfunctionname(){
//...
}
so it would create the function test()
or with classes too like:
$foo = bar;
class $foo {
// lots of complicated stuff
// ...
}
but this doesen't work. like this it would give parse errors!
Is there a solution to this?
(I know, this is not good practise, but just as a workaround, it would be handy)
EDIT: My actual problem:
I have a framework with a migration process where every migration step is in a separate php include file in a folder.
Each file contains only one migration class that contains the name of the include file.
Because the class has to have that certain name, I would like to create the name of the class to a generic name that is created by the filename constant __FILE__

Answer 1

Yes, you can, but I dont want you to.
$classname = "test";
eval("class {$classname}{ public function hello(){ echo \"hello!\"; } }");
$evil_class = new $classname();
$evil_class->hello(); // echo's "hello!"
now, if you don't mind me I'm going for a shower.

Answer 2

You can use a factory pattern:
class poly_Factory {
public function __construct() {
$class = 'poly';
return new $class();
}
}
If that is anything you want to get to.
http://net.tutsplus.com/tutorials/php/understanding-and-applying-polymorphism-in-php/
Scroll down to step 4, last part...
I know you did not ask for that, but what can your question be good for else?

Answer 3

No. This code throws a parse error on line 3 because of the $:
$foo = 'bar';
class $foo {
function hello() {
echo "World";
}
}
$mybar = new bar();
$mybar->hello();
Result:
Parse error: syntax error, unexpected T_VARIABLE, expecting T_STRING on line 3
And as Jan Dvorak pointed out in the comments: even if you figure out a way to do this, don't do this.

Answer 4

If you want to create a value object you can just use the stdClass builtin type.
$object = new stdClass;
$object->someValue = "Hello World";
echo $object->someValue;
See it in Action
If you want to assign methods then you have to use the magic __call function, here is how I would do it.
class AnonObject{
private $properties = array();
private $methods = array();
public function __get($property){
return array_key_exists($property, $this->properties)?$this->properties[$property]:null;
}
public function __set($property, $value){
if (!is_string($value) && is_callable($value)){
if ($value instanceof \Closure){
// bind the closure to this object's instance and static context
$this->methods[$property] = $value->bindTo($this,get_class($this));
} else {
// invokable objects
$this->methods[$property] = $value;
}
} else {
$this->properties[$property] = $value;
}
}
public function __call($method, $args){
if (array_key_exists($method, $this->methods)){
call_user_func_array($this->methods[$method], $args);
} else {
throw new RuntimeException("Method ".$method." does not exist on object");
}
}
}
See it In Action
Note, as stated by several other people this is bad practice. If the goal of this exercise is to compose the behavior of an instance of an object at runtime a more maintainable solution would be to use the Strategy Pattern